CN113336772B

CN113336772B - Hole transport material and synthesis method and application thereof

Info

Publication number: CN113336772B
Application number: CN202110429279.5A
Authority: CN
Inventors: 姜月; 伍业辉; 龚志明; 王茹; 高进伟
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2021-04-21
Filing date: 2021-04-21
Publication date: 2023-04-25
Anticipated expiration: 2041-04-21
Also published as: CN113336772A

Abstract

The invention discloses a hole transport material, in particular a hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group, a synthesis process of the hole transport material, application of the hole transport material in preparing a perovskite solar cell, and the perovskite solar cell prepared by using the hole transport material. The hole transport material has higher glass transition temperature, proper HOMO energy level and moderate optical band gap, and the highest photoelectric conversion efficiency of the prepared perovskite solar cell device is more than 18%; the synthesis method has simple steps and lower preparation cost.

Description

Hole transport material and synthesis method and application thereof

Technical Field

The invention belongs to the technical field of hole transport materials, and particularly relates to a hole transport material and a synthesis method and application thereof, in particular to a hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group, and a synthesis method and application thereof.

Background

Currently, excessive development and use of non-renewable energy sources represented by fossil energy sources causes problems such as increasingly serious energy exhaustion and environmental deterioration. The solar energy has the outstanding advantages of cleanness, no pollution, huge total radiation amount, no regional limitation and the like, and is widely focused by researchers.

A third generation new solar cell comprising: organic solar cells (OPVs), dye Sensitized Solar Cells (DSSCs), quantum dot solar cells (QSCs), perovskite Solar Cells (PSCs) and the like, and has the advantages of simple preparation process, solution processing, low cost and excellent application prospect. Among them, perovskite Solar Cells (PSCs) have been developed in 2009, and the Photoelectric Conversion Efficiency (PCE) thereof has been increased from the initial 3.8% to the current 25.5% over ten years, and has become one of the most competitive photovoltaic technologies in the current new energy field.

As shown in fig. 1, the perovskite solar cell device is composed of five parts, which are a transparent conductive electrode, an electron transport layer, a perovskite light absorption layer, a hole transport layer, and a metal back electrode, respectively. The hole transport material is one of key materials of perovskite solar cells, and mainly plays roles in extracting and transporting holes, blocking electrons and inhibiting accumulation and recombination at a carrier interface in a device. The ideal hole transport layer should be provided with: (1) excellent hole mobility and conductivity; (2) The matched energy level (3) has excellent dissolving capacity and film forming property; (4) High thermal stability, photochemical stability and high hydrophobicity; and (5) low commercial production cost and the like.

Common hole transport materials include inorganic, polymeric and small molecule three major classes of materials. The small molecule hole transport material has various structures and can be processed in solution, and is the hole transport layer material with the highest competitiveness. 2,2', 7' -tetrakis [ N, N-bis (4-methoxyphenyl) amino ] -9,9' -spirobifluorene (Spiro-OMeTAD) is the currently most widely used small molecule hole transport layer. However, the complex and costly synthesis route of the Spiro-OMeTAD severely limits its commercial application (ACS appl. Mater. Interfaces.2015,7 (21): 11107-11116.). Therefore, the design and development of novel efficient organic small molecule hole transport materials are one of the research hotspots in the industry.

Disclosure of Invention

The first object of the present invention is to provide a hole transport material, especially a hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group, which has good stability, low cost, easy adjustment and good hole transport performance.

The second purpose of the invention is to provide a method for synthesizing the hole transport material, in particular to a method for synthesizing the hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group.

The third object of the present invention is to provide the application of the hole transport material, especially the hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as core and carbazole as end group in perovskite solar cell.

The first object of the present invention can be achieved by the following technical means:

a hole transport material, especially a hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group, has the following structural formula:

specifically, R is different alkyl chains and is respectively n-hexyl or 2-ethylhexyl, and the structural formula of R is as follows:

specifically, X is a different side chain atom or group, and is a hydrogen atom, an alkoxy group or a halogen atom, specifically a hydrogen atom, a methoxy group or a fluorine atom, and the specific structural formula of X is as follows:

x= H, OMe or F.

The specific structural formulas of the hole transport materials with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group are TM-I-TM-VI, and are shown in figure 2.

The hole transport material of the invention introduces the capability of extracting holes of different substituent group regulating molecules on carbazole end groups by introducing the accumulation among different side chain regulating molecules on the parent nucleus.

The synthesis method of the hole transport material taking dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group is recommended to adopt the following method for preparation, and the method is specifically as follows.

The second object of the present invention can be achieved by the following technical scheme: the synthesis method of the hole transport material comprises the following steps:

(1) Mixing 3-bromo-9-phenyl-9-H-carbazole derivative and bisboronic acid pinacol ester, adding an organic solvent for dissolution, then adding a catalyst a and a base a, and fully mixing and reacting under the condition of nitrogen protection to generate 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole derivative;

(2) Selecting a 2, 6-dibromo-4-hydrogen-dithiophene [3,2-b:2',3' -d ] pyrrole derivative and the 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole derivative prepared in the step (1), adding an organic solvent for dissolution, then adding a catalyst b and a base b, and reacting under the condition of nitrogen protection to generate a target product;

(3) After the reaction is finished, extracting with water and dichloromethane in sequence, collecting an organic phase, drying, filtering, chromatography and concentration to obtain the hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group.

Further, the synthesis method of the hole transport material comprises the following steps:

(1) Mixing 3-bromo-9-phenyl-9-H-carbazole derivative and bisboronic acid pinacol ester, adding an organic solvent for dissolution, adding a catalyst a and a base a, and fully mixing and reacting under the condition of nitrogen protection to generate 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole derivative;

the synthetic route is as follows:

wherein the 3-bromo-9-phenyl-9-H-carbazole derivative is 3-bromo-9- (4-phenyl) -9H-carbazole, 3-bromo-9- (4-methoxyphenyl) -9H-carbazole or 3-bromo-9- (4-fluorophenyl) -9H-carbazole;

the 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole derivative is 9- (4-phenyl) -3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole 9- (4-methoxyphenyl) -3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole or 9- (4-fluorophenyl) -3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole;

(2) Selecting 2, 6-dibromo-4-hydrogen-dithiophene [3,2-b:2',3' -d ] pyrrole derivative and 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole derivative, adding an organic solvent for dissolution, adding a catalyst b and a base b, and carrying out Suzuki coupling reaction under the protection of nitrogen (A. Tetrahedron Lett.1979,36, 3437-3440.) to generate a target product;

the synthetic route is as follows:

specifically, X is a different side chain atom or group, specifically a hydrogen atom, methoxy group or fluorine atom, and the specific structural formula of X is as follows:

x= H, OMe or F;

wherein the 2, 6-dibromo-4-hydrogen-dithiophene [3,2-b:2',3' -d ] pyrrole derivative is 2, 6-dibromo-4- (2-ethylhexyl) -4H-dithiophene [3,2-b:2,3-d ] pyrrole or 2, 6-dibromo-4- (2-hexyl) -4H-dithiophene [3,2-b:2',3' -d ] pyrrole;

The method for synthesizing the hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group comprises the following steps:

preferably, the organic solvent in the steps (1) to (2) is anhydrous 1, 4-dioxane, and the reaction is carried out in a Schlenk reaction tube.

Preferably, the molar ratio of the 3-bromo-9-phenyl-9-H-carbazole derivative to the pinacol ester of biboronate in step (1) is 1 (1.5-2).

Preferably, the catalyst a in step (1) is dichloro [1,1' -bis (diphenylphosphino) ferrocene]Palladium (Pd (dppf) Cl) ₂ ) The amount of the 3-bromo-9-phenyl-9-H-carbazole derivative is (0.02 to 0.1): 1.

preferably, in the step (1), the base a is potassium acetate (AcOK), and the amount of the base a and the substance of the bisboronic acid pinacol ester is (2-3): 1.

preferably, the reaction temperature in the mixing reaction in the step (1) is 90-110 ℃ and the reaction time is 16-20 hours.

Preferably, the 3-bromo-9-phenyl-9-H-carbazole derivative in step (1) is 3-bromo-9- (4-phenyl) -9H-carbazole, 3-bromo-9- (4-methoxyphenyl) -9H-carbazole or 3-bromo-9- (4-fluorophenyl) -9H-carbazole.

Preferably, the method comprises the steps of, the 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole derivative in the step (1) is 9- (4-phenyl) -3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole 9- (4-methoxyphenyl) -3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole or 9- (4-fluorophenyl) -3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole

Preferably, the molar ratio of the 2, 6-dibromo-4-hydro-dithiophene [3,2-b:2',3' -d ] pyrrole derivative to the 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole derivative in step (2) is 1 (2-3).

Preferably, the 2, 6-dibromo-4-hydro-dithieno [3,2-b:2',3' -d ] pyrrole derivative in step (2) is 2, 6-dibromo-4- (2-ethylhexyl) -4H-dithieno [3,2-b:2,3-d ] pyrrole or 2, 6-dibromo-4- (2-hexyl) -4H-dithieno [3,2-b:2',3' -d ] pyrrole.

Preferably, the catalyst b in step (2) is dibenzylidene acetone dipalladium (Pd) ₂ dba ₃ ) With 2, 6-dibromo-4-hydro-dithiophene [3,2-b:2',3' -d]The amount of the pyrrole derivative is (0.02 to 0.1): 1.

preferably, the base b in step (2) is potassium phosphate trihydrate (K ₃ PO ₄ ·3H ₂ O) which has a mass relation with the substance of the 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole derivative of (2 to 3): 1.

preferably, the reaction temperature at which the reaction occurs in step (2) is 100 to 120℃and the reaction time is 16 to 20 hours.

The third object of the present invention can be achieved by the following technical scheme: the hole transport material is applied to perovskite solar cells.

The hole transport material with dithieno [3,2-b:2',3' -d ] pyrrole as the core and carbazole as the end group has higher glass transition temperature and higher hole mobility, so the material can be used as the hole transport material of the perovskite solar cell.

The invention also provides a perovskite solar cell, which has the structure comprising a transparent basal layer, an electron transport layer, a perovskite active layer, a hole transport layer, a hole blocking layer and a metal electrode layer from bottom to top, wherein the hole transport layer is mainly prepared from the hole transport material taking dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as an end group.

Preferably, the perovskite solar cell has a transparent substrate layer of fluorine doped tin oxide conductive glass (FTO).

Preferably, the perovskite solar cell is characterized in that the electron transport layer is made of tin dioxide, and the thickness of the electron transport layer is 20-40 nm.

Preferably, the perovskite solar cell is characterized in that the perovskite active layer is made of lead methylamine iodide, and the chemical structural general formula of the perovskite solar cell is CH ₃ NH ₃ PbI ₃ The thickness is 350-450 nm.

Preferably, the perovskite solar cell is characterized in that the hole transport layer is made of compounds TM-I to TM-VI (shown in figure 2) and has a thickness of 150-200 nm.

Preferably, in the perovskite solar cell, the metal electrode layer is made of silver, and the thickness is 80-100 nm.

The invention has the following advantages:

(1) Compared with the Spiro-OMeTAD material, the hole transport synthesis method with dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group has simple steps and lower preparation cost, and the material has higher glass transition temperature and proper HOMO energy level, so that the material can be used as a hole transport material of a perovskite solar cell;

(2) The hole transport material has higher hole mobility, can be used in perovskite solar cells, and can obtain higher open-circuit voltage (V) _OC ) Short-circuit current (J) _SC ) And Fill Factor (FF), resulting in a higher Photoelectric Conversion Efficiency (PCE), wherein TM-ii and TM-iii based devices achieve a photoelectric conversion efficiency of over 18%.

Drawings

FIG. 1 is a schematic diagram of a perovskite solar cell structure in the background;

FIG. 2 is a schematic illustration of the chemical structural formula of the organic hole transport materials TM-I, TM-II, TM-III, TM-IV, TM-V, TM-2, TM-3, TM-4 of the summary of the invention;

FIG. 3 shows the hydrogen nuclear magnetic resonance spectrum of the organic hole transporting material TM-I of example 3 ¹ H NMR)；

FIG. 4 shows nuclear magnetic resonance spectrum of the organic hole transporting material TM-I of example 3 ¹³ C NMR)；

FIG. 5 is a high resolution mass spectrum of organic hole transport material TM-I of example 3;

FIG. 6 shows the hydrogen nuclear magnetic resonance spectrum of the organic hole transporting material TM-II of example 4 ¹ H NMR)；

FIG. 7 shows nuclear magnetic resonance spectrum of the organic hole transporting material TM-II of example 4 ¹³ C NMR)；

FIG. 8 is a MALDI-TOF mass spectrum of the organic hole transporting material TM-II of example 4;

FIG. 9 shows the hydrogen nuclear magnetic resonance spectrum of the organic hole transporting material TM-III of example 5 ¹ H NMR)；

FIG. 10 shows nuclear magnetic resonance spectrum of organic hole transporting material TM-III in example 5 ¹³ C NMR)；

FIG. 11 shows nuclear magnetic resonance fluorine spectrum of organic hole transporting material TM-III in example 5 ¹⁹ F NMR)；

FIG. 12 is a high resolution mass spectrum of organic hole transport material TM-III in example 5;

FIG. 13 is example 6Nuclear magnetic resonance hydrogen spectrum of organic hole transport material TM-IV ¹ H NMR)；

FIG. 14 shows nuclear magnetic resonance spectrum [. About. ¹³ C NMR)；

FIG. 15 is a high resolution mass spectrum of organic hole transport material TM-IV of example 6;

FIG. 16 shows the hydrogen nuclear magnetic resonance spectrum of the organic hole transporting material TM-V of example 7 ¹ H NMR)；

FIG. 17 shows nuclear magnetic resonance spectrum of the organic hole transporting material TM-V of example 7 ¹³ C NMR)；

FIG. 18 is a high resolution mass spectrum of organic hole transporting material TM-V of example 7;

FIG. 19 shows the hydrogen nuclear magnetic resonance spectrum of the organic hole transporting material TM-VI of example 8 ¹ H NMR)；

FIG. 20 shows nuclear magnetic resonance spectrum of organic hole transporting material TM-VI in example 8 ¹³ C NMR)；

FIG. 21 shows nuclear magnetic resonance fluorine spectrum of the organic hole transporting material TM-VI of example 8 ¹⁹ F NMR)；

FIG. 22 is a high resolution mass spectrum of organic hole transport material TM-VI of example 8;

FIG. 23 is a Cyclic Voltammogram (CV) of organic hole transporting materials TM-I through TM-VI of examples 3-8, wherein A is TM-I, B is TM-II, C is TM-III, D is TM-IV, E is TM-V, and F is TM-VI;

FIG. 24 is an ultraviolet-visible spectrum absorption spectrum (UV-vis) of a film and a solution of organic hole transporting materials TM-I to TM-VI of examples 3 to 8, wherein A is TM-I, B is TM-II, C is TM-III, D is TM-IV, E is TM-V, F is TM-VI;

FIG. 25 is a thermogravimetric analysis (TGA) of the organic hole transport materials TM-I-TM-VI of examples 3-8, wherein A is TM-I, B is TM-II, C is TM-III, D is TM-IV, E is TM-V, F is TM-VI;

FIG. 26 is a Differential Scanning Calorimetry (DSC) curve of organic hole-transporting materials TM-I-TM-VI of examples 3-8 wherein A is TM-I, B is TM-II, C is TM-III, D is TM-IV, E is TM-V, and F is TM-VI;

fig. 27 is a perovskite solar cell device structure in example 9;

fig. 28 is a J-V characteristic curve of the device based on the different hole transport materials in example 9.

Detailed Description

The invention will be further illustrated with reference to the following specific examples, but the invention is not limited to the following examples. The methods are conventional methods unless otherwise specified, and the starting materials are commercially available from the public sources unless otherwise specified.

Example 1: synthesis of 9- (4-methoxyphenyl) -3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole (intermediate 1)

Synthetic route to intermediate 1:

into a 50mL Schlenk reaction tube was charged the compound 3-bromo-9- (4-methoxyphenyl) -9H-carbazole (1.72 g,4.89 mmol), pinacol biborate (1.86 g,7.34 mmol), pd (dppf) Cl ₂ (73 mg,0.1 mmol), potassium acetate (1.4 g,14.67 mmol) and anhydrous 1, 4-dioxane (20 mL) were then purged three more times and reacted at 90℃for 16 hours under nitrogen.

After the reaction was completed, the reaction solution was cooled to room temperature, 50mL of water was then added to the reaction solution, and the aqueous phase was extracted three times with methylene chloride, and the organic phase was extracted with anhydrous Na ₂ SO ₄ After drying, the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate=10:1 as eluent) to give intermediate 1 (1.27 g, 65%) as a white solid.

Example 2: synthesis of 9- (4-fluorophenyl) -3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole (intermediate 2)

Synthetic route to intermediate 2:

into a 50mL Schlenk reaction tube was charged the compound 3-bromo-9- (4-fluorophenyl) -9H-carbazole (2.18 g,6.13 mmol), pinacol biborate (2.32 g,9.20 mmol), pd (dppf) Cl ₂ (90 mg,0.12 mmol), potassium acetate (1.8 g,18.39 mmol) and anhydrous 1, 4-dioxane (30 mL) were then purged three more times and reacted at 90℃for 16 hours under nitrogen.

After the reaction was completed, the reaction solution was cooled to room temperature, 50mL of water was then added to the reaction solution, and the aqueous phase was extracted three times with methylene chloride, and the organic phase was extracted with anhydrous Na ₂ SO ₄ After drying, the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether: ethyl acetate=25:1 as eluent) to give intermediate 2 (2 g, 84% yield) as a white solid;

example 3:4- (2-ethylhexyl) -2, 6-bis (9-phenyl-9H-carbazol-3-yl) -4H-dithio [3,2-b: synthesis and characterization of 2',3' -d pyrrole (TM-I)

Synthetic route to TM-I:

into a 50mL Schlenk reaction tube was charged the compound 2, 6-dibromo-4- (2-ethylhexyl) -4H-dithioeno [3,2-b:2,3-d]Pyrrole (170 mg,0.38 mmol), 9- (4-hydrogen) -phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl) -9H-carbazole (280 mg,0.76 mmol), pd (PPh) ₃ ) ₄ (9mg，0.008mmol)，K ₃ PO ₄ ·3H ₂ O (404 mg,1.52 mmol) and 1, 4-dioxane (5 mL) were reacted at 100deg.C under nitrogen for 16 hours.

After the reaction was completed, the reaction solution was cooled to room temperature, 50mL of water was then added to the reaction solution, and the aqueous phase was extracted three times with methylene chloride, and the organic phase was extracted with anhydrous Na ₂ SO ₄ After drying, the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether: dichloromethane=2:1 as eluent) to give TM-i (200 mg, 68% yield) as a yellow solid.

Organic compoundNuclear magnetic resonance hydrogen spectrum of hole transport material TM-I ¹ H NMR) as shown in FIG. 3, nuclear magnetic resonance carbon spectrum [ ] ¹³ C NMR) as shown in fig. 4, the NMR characterization data is as follows: ¹ H NMR(600MHz,C ₆ D ₆ ):8.64(d,J＝1.8Hz,2H),8.02(dd,J ₁ ＝7.2Hz,J ₂ ＝1.2Hz,2H),7.83(dd,J ₁ ＝8.4Hz,J ₂ ＝1.2Hz,2H),7.37(s,2H),7.29-7.26(m,6H),7.24-7.20(m,2H),7.18-7.16(m,6H),7.14-7.13(m,2H),3.90-3.80(m,2H),2.03-1.98(m,1H),1.35-1.15(m,8H),0.86(t,J＝7.2Hz,3H),0.78(t,J＝7.2Hz,3H). ¹³ C NMR(150MHz,C ₆ D ₆ ) 145.49,143.16,141.59,140.44,137.63,129.66,128.66,127.13,126.95,126.29,124.50,124.34,123.61,120.70,120.30,117.44,114.50,110.30,109.93,106.53,50.99,40.31,30.56,28.47,24.03,23.05,13.96,10.52 the structure of the material TM-I can be determined by the peak position and the number of hydrogens corresponding thereto. The high resolution mass spectrum of the organic hole transport material TM-I is shown in FIG. 5, and the accuracy of the structure is further demonstrated by mass spectrum.

The properties of the material itself were then characterized, as shown in FIG. 23, panel A, with a HOMO level of-5.16 eV for TM-I as measured by Cyclic Voltammetry (CV); as shown in FIG. 24A, the maximum absorption peak in the solution state was found to be 402nm by ultraviolet-visible absorption spectroscopy (UV-Vis), the absorption band edge was 500nm, and the optical band gap was 2.48eV, indicating that the HOMO energy level of material TM-I was matched to that of perovskite. FIG. 25A is a thermogravimetric analysis of a material with a thermal decomposition temperature of 422℃and FIG. 26A is a differential scanning calorimeter curve of a material with a glass transition temperature T of TM-I _g At 91 ℃, it is shown that material TM-I has good thermal properties.

Example 4:4- (2-ethylhexyl) -2, 6-bis (9- (4-methoxyphenyl) -9H-carbazol-3-yl) -4H-dithio [3,2-b: synthesis and characterization of 2',3' -d pyrrole (TM-II)

Synthetic route to TM-II:

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into a 50mL Schlenk reaction tube was charged the compound 2, 6-dibromo-4- (2-ethylhexyl) -4H-dithioeno [3,2-b:2,3-d]Pyrrole (225 mg,0.5 mmol), intermediate 1 (418 mg,1.0 mmol), pd (PPh) ₃ ) ₄ (11mg，0.01mmol)，K ₃ PO ₄ ·3H ₂ O (532 mg,2.0 mmol) and 1, 4-dioxane (5 mL) were reacted at 100deg.C under nitrogen for 16 hours.

After the reaction was completed, the reaction solution was cooled to room temperature, 50mL of water was then added to the reaction solution, and the aqueous phase was extracted three times with methylene chloride, and the organic phase was extracted with anhydrous Na ₂ SO ₄ After drying, the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether: dichloromethane=2:1 as eluent) to give TM-ii (310 mg, yield 72%) as a yellow solid.

Nuclear magnetic resonance hydrogen spectrum of organic hole transport material TM-II ¹ H NMR) as shown in FIG. 6, nuclear magnetic resonance carbon spectrum [ ] ¹³ C NMR) as shown in fig. 7, the NMR characterization data is as follows: ¹ H NMR(600MHz,C ₆ D ₆ ):8.68(d,J＝1.8Hz,2H),8.06(d,J＝7.8Hz,2H),7.88(dd,J ₁ ＝8.4Hz,J ₂ ＝1.8Hz,2H),7.38(s,2H),7.35-7.29(m,6H),7.26-7.23(m,2H),7.09-7.07(m,4H),6.78-6.75(m,4H),3.92-3.83(m,2H),3.32(s,6H),2.03-1.99(m,1H),1.37-1.15(m,8H),0.86(t,J＝7.2Hz,3H),0.78(t,J＝7.2Hz,3H). ¹³ C NMR(150MHz,C ₆ D ₆ ) 158.98,145.48,143.25,142.15,141.00,130.11,128.46,128.40,126.26,124.48,124.12,123.41,120.72,120.09,117.48,114.97,114.47,110.26,109.90,106.49,54.72,51.00,40.31,30.56,28.47,23.06,13.97,10.53 by the peak position and the number of hydrogens corresponding thereto, the structure of the material TM-II can be determined. MALDI-TOF mass spectrum of organic hole transport material TM-II is shown in FIG. 8, and the accuracy of the structure is further demonstrated by mass spectrum.

Characterization of the properties of the material itself, as shown in FIG. 23, panel B, shows that the HOMO level of TM-II is-5.14 eV as measured by Cyclic Voltammetry (CV); as shown in a diagram B in FIG. 24, the maximum absorption peak in the solution state measured by ultraviolet-visible absorption spectrum (UV-Vis) is 402nm, the absorption band edge is 457nm, the optical band gap is 2.71eV, and the material is illustratedThe HOMO level of TM-II is matched to the perovskite level. FIG. 25B is a graph of the thermogravimetric analysis of a material with a thermal decomposition temperature of 435 ℃; FIG. 26B is a differential scanning calorimetry curve of the material, the glass transition temperature T of the material TM-II _g The temperature is 101 ℃, which shows that the material TM-II has good thermal property.

Example 5:4- (2-ethylhexyl) -2, 6-bis (9- (4-fluorophenyl) -9H-carbazol-3-yl) -4H-dithio [3,2-b: synthesis and characterization of 2',3' -d pyrrole (TM-III)

Synthetic route to TM-III:

into a 50mL Schlenk reaction tube was charged the compound 2, 6-dibromo-4- (2-ethylhexyl) -4H-dithioeno [3,2-b:2,3-d]Pyrrole (225 mg,0.5 mmol), intermediate 2 (387 mg,1.0 mmol), pd (PPh) ₃ ) ₄ (11mg，0.01mmol)，K ₃ PO ₄ ·3H ₂ O (532 mg,2.0 mmol) and 1, 4-dioxane (5 mL) were reacted at 100deg.C under nitrogen for 16 hours.

After the reaction was completed, the reaction solution was cooled to room temperature, 50mL of water was then added to the reaction solution, and the aqueous phase was extracted three times with methylene chloride, and the organic phase was extracted with anhydrous Na ₂ SO ₄ After drying, the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether: dichloromethane=2:1 as eluent) to give TM-iii as a yellow solid (282 mg, 70% yield).

Nuclear magnetic resonance hydrogen spectrum of organic hole transport material TM-III ¹ H NMR) as shown in FIG. 9, nuclear magnetic resonance carbon spectrum [ ] ¹³ C NMR) As shown in FIG. 10, nuclear magnetic resonance fluorine spectrum [ ] ¹⁹ F NMR) as shown in fig. 11, the NMR characterization data is as follows: ¹ H NMR(600MHz,DMSO-d6):8.59(s,2H),8.36(d,J＝7.8Hz,2H),7.77(s,4H),7.60-7.55(m,8H),7.48-7.46(m,2H),7.41-7.37(m,4H),7.35-7.32(m,2H),4.27-4.26(m,2H),2.60(s,6H),2.15-2.10(m,1H),1.41-1.21(m,8H),0.93(t,J＝7.2Hz,3H),0.85(t,J＝7.2Hz,3H). ¹³ C NMR(150MHz,DMSO-d6):145.65,141.94,141.24,139.96,138.45,133.83,128.08,127.75,127.70,127.15,124.29,123.81,121.33,120.77,117.11,112.94,110.71,110.31,108.04,51.13,40.28,30.28,28.15,23.79,23.15,15.19,14.37,10.97. ¹⁹ f NMR (564 MHz, DMSO-d 6): 113.66, the structure of the material TM-III can be determined by the peak position and the number of hydrogens corresponding thereto. The high resolution mass spectrum of the organic hole transport material TM-III is shown in FIG. 12, and the accuracy of the structure is further demonstrated by mass spectrum.

Characterization of the properties of the material itself, as shown in graph C of FIG. 23, shows that the HOMO level of TM-III is-5.17 eV as measured by Cyclic Voltammetry (CV); as shown in FIG. 24C, the maximum absorption peak in the solution state was found to be 401nm by ultraviolet-visible absorption spectroscopy (UV-Vis), the absorption band edge was 465nm, and the optical band gap was 2.66eV, indicating that the HOMO energy level of material TM-III was matched to that of perovskite. FIG. 25C is a thermogravimetric analysis of a material with a thermal decomposition temperature of 426℃and FIG. 26C is a differential scanning calorimeter curve of a material with a glass transition temperature T of TM-III _g The temperature is 103 ℃, which shows that the material TM-III has good thermal property.

Example 6: 4-hexyl-2, 6-bis (9-phenyl-9H-carbazol-3-yl) -4H-dithio [3,2-b: synthesis and characterization of 2',3' -d pyrrole (TM-IV)

The synthetic route of TM-IV:

into a 50mL Schlenk reaction tube was charged the compound 2, 6-dibromo-4-hexyl-4H-thieno [3,2-b:2',3' -d]Pyrrole (210 mg,0.5 mmol), 9-phenyl-3- (4, 5-tetramethyl-1, 3, 2-dioxaborane-2-yl) -9H-carbazole (369 mg,1.0 mmol), pd (PPh ₃ ) ₄ (11mg，0.01mmol)，K ₃ PO ₄ ·3H ₂ O (532 mg,2.0 mmol) and 1, 4-dioxane (5 mL) were reacted at 100deg.C under nitrogen for 16 hours.

After the reaction was completed, the reaction solution was cooled to room temperature, 50mL of water was then added to the reaction solution, and the aqueous phase was extracted three times with methylene chloride, and the organic phase was extracted with anhydrous Na ₂ SO ₄ After drying, the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether: dichloromethane=2:1 as eluent) to give TM-iv (200 mg, 53% yield) as a yellow solid.

Nuclear magnetic resonance hydrogen spectrum of organic hole transport material TM-IV ¹ H NMR) as shown in FIG. 13, nuclear magnetic resonance carbon spectrum [ ] ¹³ C NMR) as shown in fig. 14, the NMR characterization data is as follows: ¹ H NMR(600MHz,DMSO-d6):8.62(s,2H),8.36(d,J＝8.4Hz,2H),7.83(s,2H),7.79-7.77(m,2H),7.72-7.70(m,4H),7.67-7.65(m,4H),7.58-7.55(m,2H),7.49-7.46(m,2H),7.42-7.39(m,4H),7.35-7.33(m,2H),4.38(t,J＝7.2Hz,3H),1.96-1.91(m,2H),1.41-1.26(m,6H),0.85(t,J＝7.2Hz,3H). ¹³ c NMR (150 MHz, DMSO-d 6): 156.56,145.37,141.97,141.19,139.90,137.17,130.73,128.28,128.14,127.17,127.14,124.29,123.87,123.16,121.33,120.82,117.13,112.98,110.72,110.32,108.02,43.95,31.39,30.44,26.54,22.61,14.39, the structure of the material TM-IV can be determined by the peak position and the number of hydrogens corresponding thereto. MALDI-TOF mass spectrum of organic hole transport material TM-IV is shown in FIG. 15, and the accuracy of the structure is further demonstrated by mass spectrum.

Characterization of the properties of the material itself, as shown in the graph D of FIG. 23, the HOMO level of TM-IV was-5.11 eV as measured by Cyclic Voltammetry (CV); as shown in the graph D in FIG. 24, the maximum absorption peak in the solution state is 402nm, the absorption band edge is 506nm, and the optical band gap is 2.45eV, as measured by ultraviolet-visible absorption spectrum (UV-Vis), which shows that the HOMO energy level of the material TM-IV is matched with the energy level of perovskite. FIG. 25D is a graph of the thermogravimetric analysis of a material with a thermal decomposition temperature of 416 ℃; FIG. 26D is a differential scanning calorimetry curve of the material, the glass transition temperature T of the material TM-IV _g The temperature is 104 ℃, which shows that the materials TM-IV have good thermal properties.

Example 7: 4-hexyl-2, 6-bis (9- (4-methoxyphenyl) -9H-carbazol-3-yl) -4H-dithio [3,2-b: synthesis and characterization of 2',3' -d pyrrole (TM-V)

Synthetic route to TM-V:

into a 50mL Schlenk reaction tube was charged the compound 2, 6-dibromo-4-hexyl-4H-thieno [3,2-b:2',3' -d]Pyrrole (187 mg,0.44 mmol), intermediate 1 (350 mg,0.89 mmol), pd (PPh) ₃ ) ₄ (11mg，0.01mmol)，K ₃ PO ₄ ·3H ₂ O (532 mg,2.0 mmol) and 1, 4-dioxane (5 mL) were reacted at 100deg.C under nitrogen for 16 hours.

After the reaction was completed, the reaction solution was cooled to room temperature, 50mL of water was then added to the reaction solution, and the aqueous phase was extracted three times with methylene chloride, and the organic phase was extracted with anhydrous Na ₂ SO ₄ After drying, the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether: dichloromethane=1:1 as eluent) to give TM-v (250 mg, 70% yield) as a yellow solid.

Nuclear magnetic resonance hydrogen spectrum of organic hole transport material TM-V ¹ H NMR) as shown in FIG. 16, nuclear magnetic resonance carbon spectrum [ ] ¹³ C NMR) as shown in fig. 17, the NMR characterization data is as follows: ¹ H NMR(600MHz,DMSO-d6):8.60(s,2H),8.34(d,J＝7.2Hz,2H),7.82-7.75(m,4H),7.56-7.54(m,4H),7.47-7.44(m,2H),7.34-7.30(m,6H),7.25-7.23(m,4H),4.38(s,2H),3.90(s,6H),1.96-1.91(m,2H),1.41-1.33(m,4H),1.32-1.24(m,2H),0.86(t,J＝7.8Hz,3H). ¹³ c NMR (150 MHz, DMSO-d 6): 159.11,145.32,142.04,141.68,140.40,129.64,128.68,127.05,124.23,123.60,122.89,121.25,117.09,115.85,112.88,110.71,110.24,107.89,55.97,47.08,31.39,30.44,26.54,22.62,14.39, the structure of the material TM-V can be determined by the peak position and the number of hydrogens corresponding thereto. The high resolution mass spectrum of the organic hole transport material TM-v is shown in fig. 18, and the accuracy of the structure is further demonstrated by mass spectrum.

Characterization of the nature of the material itself, as shown in FIG. 23, E, shows that the HOMO level of TM-V is-5.14 eV as measured by Cyclic Voltammetry (CV); as shown in the E graph in FIG. 24, the maximum absorption peak in the solution state measured by ultraviolet-visible absorption spectrum (UV-Vis) is at 404nm, the absorption band edge is 465nm, the optical band gap is 2.66eV, illustrating the HOMO level of the material TM-V and calciumThe energy levels of the titanium ore are matched. FIG. 25, E, is a thermogravimetric analysis curve of a material with a thermal decomposition temperature of 436℃and FIG. 26, is a differential scanning calorimeter curve of a material with a glass transition temperature T of a material TM-V _g At 106 ℃, it is demonstrated that the material TM-v has good thermal properties.

Example 8:2, 6-bis (9- (4-fluorophenyl) -9H-carbazol-3-yl) -4-hexyl-4H-dithio [3,2-b: synthesis and characterization of 2',3' -d pyrrole (TM-VI)

Synthetic route to TM-VI:

into a 50mL Schlenk reaction tube was charged the compound 2, 6-dibromo-4-hexyl-4H-thieno [3,2-b:2',3' -d]Pyrrole (210 mg,0.5 mmol), intermediate 2 (387 mg,1.0 mmol), pd (PPh) ₃ ) ₄ (11mg，0.01mmol)，K ₃ PO ₄ ·3H ₂ O (532 mg,2.0 mmol) and 1, 4-dioxane (5 mL) were reacted at 100deg.C under nitrogen for 16 hours.

After the reaction was completed, the reaction solution was cooled to room temperature, 50mL of water was then added to the reaction solution, and the aqueous phase was extracted three times with methylene chloride, and the organic phase was extracted with anhydrous Na ₂ SO ₄ After drying, the solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography (petroleum ether: dichloromethane=2:1 as eluent) to give TM-vi as a yellow solid (240 mg, 61% yield).

Nuclear magnetic resonance hydrogen spectrum of organic hole transport material TM-VI ¹ H NMR) as shown in FIG. 19, nuclear magnetic resonance carbon spectrum [ ] ¹³ C NMR) As shown in FIG. 20, nuclear magnetic resonance fluorine spectrum [ ] ¹⁹ F NMR) as shown in fig. 21, the NMR characterization data is as follows: ¹ H NMR(600MHz,DMSO-d6):8.61(s,2H),8.36(d,J＝7.8Hz,2H),7.83(s,2H),7.78(d,J＝8.4Hz,2H),7.73-7.69(m,4H),7.56-7.52(m,4H),7.49-7.46(m,2H),7.39-7.33(m,6H),4.38(t,J＝7.2Hz,3H),1.96-1.91(m,2H),1.41-1.26(m,6H),0.86(t,J＝7.2Hz,3H). ¹³ C NMR(150MHz,DMSO-d6):162.39,160.76,145.36,141.94,141.38,140.11,133.42,129.57,128.17,127.19,124.30,123.79,123.07,121.32,120.84,117.68,117.53,117.12,112.97,110.63,110.22,108.04,47.09,31.39,30.44,26.54,22.61,14.39. ¹⁹ f NMR (564 MHz, DMSO-d 6): 113.67, the structure of the material TM-VI can be determined by the peak position and the number of hydrogens corresponding thereto. The high resolution mass spectrum of the organic hole transport material TM-VI is shown in FIG. 22, and the accuracy of the structure is further demonstrated by mass spectrum.

Characterization of the properties of the material itself, as shown in FIG. 23, panel F, shows that the HOMO level of TM-VI is-5.16 eV as measured by Cyclic Voltammetry (CV); as shown in the F graph in FIG. 24, the maximum absorption peak in the solution state is 404nm as measured by ultraviolet-visible absorption spectrum (UV-Vis), the absorption band edge is 520nm, and the optical band gap is 2.38eV, which indicates that the HOMO energy level of the material TM-VI is matched with the energy level of perovskite. FIG. 25, panel F, shows the thermogravimetric analysis of a material with a thermal decomposition temperature of 414℃and FIG. 26, the differential scanning calorimeter curve of a material with a glass transition temperature T of TM-VI _g The material TM-VI has good thermal properties at 104 ℃.

Example 9: perovskite solar cells are prepared based on hole transport materials TM-I to TM-VI.

(1) Preparing a hole transport layer solution: the hole transport materials TM-I to TM-VI and the Spiro-OMeTAD prepared in examples 3 to 8 are respectively dissolved in chlorobenzene with the concentration of 0.06mol/L and stirred for 4 to 12 hours at normal temperature;

(2) Preparing an electron transport layer: spin coating tin oxide sol with the concentration of 0.1mol/L on FTO conductive glass by adopting a spin coating method, wherein the spin coating process comprises the following steps: 500r/min for 3s, then 3000r/min for 30s, and then annealing at 100 ℃ for 60 minutes to obtain an electron transport layer, wherein the thickness of the electron transport layer is 30nm;

(3) Preparation of perovskite active layer: the perovskite precursor liquid is prepared by mixing and stirring lead iodide and iodomethylamine with the mass ratio of 1:0.8-1.15 in a solvent with the volume ratio of 4:1 being N-N-dimethylformamide and dimethyl sulfoxide for 12 hours. Spin coating the perovskite precursor liquid on the surface coated with the electron transport layer in the step (2) by adopting a spin coating method, wherein the spin coating process comprises the following steps: 800r/min for 3s, then 4000r/min for 30s, and dropwise adding 400 microliters of chlorobenzene as an antisolvent in the spin coating process, and then annealing at 100 ℃ for 15 minutes to obtain a perovskite light absorption layer, wherein the thickness of the perovskite light absorption layer is 450nm;

(4) Preparing a hole transport layer: respectively spin-coating the hole transport layer solution prepared in the step (1) on the surface coated with the perovskite layer by adopting a spin-coating method, wherein the spin-coating process is 500r/min for 3s, and then 5000r/min for 30s, so as to prepare a hole transport layer, and the thickness of the hole transport layer is 180nm;

(5) Evaporating silver electrode: a silver electrode is arranged on the surface of the hole transport layer by adopting a thermal evaporation method, and the thickness of the silver electrode is 80nm; the rate of thermal evaporation was

The thermal evaporation time was 10min.

The structure of the prepared perovskite solar cell is as follows: FTO/SnO ₂ /CH ₃ NH ₃ PbI ₃ HTL/Ag as shown in FIG. 27. At an illumination intensity of 100mW/cm ² Under the irradiation of AM1.5 simulated sunlight, various photovoltaic parameters of devices based on different hole transport materials TM-I to TM-VI are shown in the following table 1, J-V characteristic curves of the devices are shown in figure 28, and the difference of conversion efficiency of perovskite solar cells prepared based on different hole transport materials is found, which shows that accumulation among different side chain adjustable molecules is introduced into a parent nucleus, the capability of extracting holes of the molecules with different substituent groups is introduced into a carbazole end group, and a conjugated system is increased by introducing a lone pair electron group into a side chain in comparison with TM-I, TM-II and TM-III, so that the charge transport performance of the materials is improved. Among them, devices based on TM-II and TM-III show a photoelectric conversion efficiency of > 18% (18.12% and 18.02%) which is close to that of the spiro-OMeTAD (19.98%), with great potential for application.

Table 1 photovoltaic parameters of devices based on different hole transport materials

It should be noted that the above description is only a non-limiting embodiment of the present invention, and any modification or variation within the meaning and scope equivalent to the technical solution of the present invention by those skilled in the art should be considered as being included in the scope of the present invention.

Claims

1. The hole transport material is characterized by having any one of the following structural formulas:

。

2. use of the hole transport material according to claim 1 in perovskite solar cells.

3. The perovskite solar cell is characterized in that the perovskite solar cell comprises a transparent substrate layer, an electron transport layer, a perovskite active layer, a hole transport layer, a hole blocking layer and a metal electrode layer from bottom to top, and the perovskite solar cell comprises the following components: the hole transport layer is mainly prepared from a hole transport material taking dithieno [3,2-b:2',3' -d ] pyrrole as a core and carbazole as a terminal group in claim 1.

4. A perovskite solar cell according to claim 3, characterized by: the transparent substrate layer is fluorine-doped tin oxide conductive glass (FTO); the electron transport layer is made of tin dioxide and has a thickness of 20-40 nm; the perovskite active layer is made of lead methyl iodide, and the chemical structural general formula of the perovskite active layer is CH ₃ NH ₃ PbI ₃ The thickness is 350-450 nm; the thickness of the hole transport layer is 150-200 nm, the material of the metal electrode layer is silver, and the thickness is 80-100 nm.